(a) Field of the Invention
The present invention provides a photomask case, and more particularly provides a photomask case structure able to firmly fix position of a photomask.
(b) Description of the Prior Art
A “wafer” is the most important material for manufacturing semiconductors, and the primary raw material for manufacturing wafers is silicon dioxide. A piece of wafer undergoes several hundred processing programs, including deposition, etching, heating, photoresist processing, coating, developing, and so on, whereby dozens, even several hundreds of microcircuit semiconductors can be manufactured from one piece of wafer depending on its size. Moreover, in order to manufacture wafers provided with different electric circuits and electronic components, preplanning of the photomask must be implemented.
The photomask can be said to be the mold for manufacturing the wafer. When a microcircuit company plans out a circuit design drawing for a chip, then the circuit design drawing must be sent to the photomask manufacturing company to implement manufacture of the photomask. The photomask manufacturing company is then able to design and plan out the corresponding photomask based on the circuit design drawing. The more complex and precise the circuit design, the more photomask layers required.
Furthermore, in order to use the photomask to plan and design the circuit design on the wafer, then the application of optical micro-imaging technology is necessary. Optical micro-imaging technology uses the exposure principle, whereby, a specific pattern can be exposed and revealed when light is transmitted through the photomask and projected onto the wafer.
However, the following problems and shortcomings are still in need of improvement when using the aforementioned photomask:
Because any tiny dust particles attached to the photomask will result in poor quality in the projected image, thus, cleanness is extremely important when used to produce developed image photomasks.